It may be time for Steve Ballmer to crank up his famous “Developers, developers, developers!” chant again if it will get software developers more excited about Windows Phone 8. Sameer Singh at Tech-Thoughts has charted the growth history of the three major mobile app stores and has found that Windows Phone’s app store is lagging behind where iOS and Android were 30 months after their initial launches. What’s more, he’s found that the additions of new apps to the Windows Phone 8 app market have markedly slowed over the past six months, whereas iOS and Android both saw significant rises in app additions over the same periods after their initial launches. Singh speculates that the slowdown in interest from developers is due to “limited install base, low user engagement, monetization challenges and regional developer restrictions,” among other factors.